Refactor ipautil.run

The ipautil.run function now returns an object with returncode and
output are accessible as attributes.

The stdout and stderr of all commands are logged (unless skip_output is given).

The stdout/stderr contents must be explicitly requested with a keyword
argument, otherwise they are None.
This is because in Python 3, the output needs to be decoded, and that can
fail if it's not decodable (human-readable) text.

The raw (bytes) output is always available from the result object,
as is "leniently" decoded output suitable for logging.

All calls are changed to reflect this.

A use of Popen in cainstance is changed to ipautil.run.

Reviewed-By: Jan Cholasta <jcholast@redhat.com>

install/oddjob/com.redhat.idm.trust-fetch-domains

@@ -26,9 +26,8 @@ def retrieve_keytab(api, ccache_name, oneway_keytab_name, oneway_principal):
     if os.path.isfile(oneway_keytab_name):
         os.unlink(oneway_keytab_name)
 
-    (stdout, stderr, retcode) = ipautil.run(getkeytab_args,
-                                            env={'KRB5CCNAME': ccache_name, 'LANG': 'C'},
-                                            raiseonerr=False)
+    ipautil.run(getkeytab_args, env={'KRB5CCNAME': ccache_name, 'LANG': 'C'},
+                raiseonerr=False)
     # Make sure SSSD is able to read the keytab
     try:
         sssd = pwd.getpwnam('sssd')